New evidence of direct oral anticoagulation therapy on cardiac valve calcifications, renal preservation and inflammatory modulation.

BACKGROUND: Rivaroxaban is a direct inhibitor of activated Factor X (FXa), an anti-inflammatory protein exerting a protective effect on the cardiac valve and vascular endothelium. We compare the effect of Warfarin and Rivaroxaban on inflammation biomarkers and their contribution to heart valve calcification progression and renal preservation in a population of atrial fibrillation (AF) patients with chronic kidney disease (CKD) stage 3b - 4. METHODS: This was an observational, multicenter, prospective study enrolling 347 consecutive CKD stage 3b - 4 patients newly diagnosed with AF: 247 were treated with Rivaroxaban and 100 with Warfarin. Every 12 months, we measured creatinine levels and cardiac valve calcification via standard trans-thoracic echocardiogram, while plasma levels of inflammatory mediators were quantified by ELISA at baseline and after 24 months. RESULTS: Over a follow-up of 24 months, long-term treatment with Rivaroxaban was associated with a significative reduction of cytokines. Patients treated with Rivaroxaban experienced a more frequent stabilization/regression of valve calcifications comparing with patients treated with Warfarin. Rivaroxaban use was related with an improvement in kidney function in 87.4% of patients, while in those treated with Warfarin was reported a worsening of renal clearance in 98% of cases. Patients taking Rivaroxaban experienced lower adverse events (3.2% vs 49%, p-value <0.001). CONCLUSIONS: Our findings suggest that Rivaroxaban compared to Warfarin is associated with lower levels of serum markers of inflammation. The inhibition of FXa may exert an anti-inflammatory effect contributing to reduce the risk of cardiac valve calcification progression and worsening of renal function.

AtlA Mediates Extracellular DNA Release, Which Contributes to Streptococcus mutans Biofilm Formation in an Experimental Rat Model of Infective Endocarditis.

Host factors, such as platelets, have been shown to enhance biofilm formation by oral commensal streptococci, inducing infective endocarditis (IE), but how bacterial components contribute to biofilm formation in vivo is still not clear. We demonstrated previously that an isogenic mutant strain of Streptococcus mutans deficient in autolysin AtlA (ΔatlA) showed a reduced ability to cause vegetation in a rat model of bacterial endocarditis. However, the role of AtlA in bacterial biofilm formation is unclear. In this study, confocal laser scanning microscopy analysis showed that extracellular DNA (eDNA) was embedded in S. mutans GS5 floes during biofilm formation on damaged heart valves, but an ΔatlA strain could not form bacterial aggregates. Semiquantification of eDNA by PCR with bacterial 16S rRNA primers demonstrated that the ΔatlA mutant strain produced dramatically less eDNA than the wild type. Similar results were observed with in vitro biofilm models. The addition of polyanethol sulfonate, a chemical lysis inhibitor, revealed that eDNA release mediated by bacterial cell lysis is required for biofilm initiation and maturation in the wild-type strain. Supplementation of cultures with calcium ions reduced wild-type growth but increased eDNA release and biofilm mass. The effect of calcium ions on biofilm formation was abolished in ΔatlA cultures and by the addition of polyanethol sulfonate. The VicK sensor, but not CiaH, was found to be required for the induction of eDNA release or the stimulation of biofilm formation by calcium ions. These data suggest that calcium ion-regulated AtlA maturation mediates the release of eDNA by S. mutans, which contributes to biofilm formation in infective endocarditis.

Heart dysfunction induced by choline-deficiency in adult rats: the protective role of L-carnitine.

Choline is a B vitamin co-factor and its deficiency seems to impair heart function. Carnitine, a chemical analog of choline, has been used as adjunct in the management of cardiac diseases. The study investigates the effects of choline deficiency on myocardial performance in adult rats and the possible modifications after carnitine administration. Wistar Albino rats (n=24), about 3 months old, were randomized into four groups fed with: (a) standard diet (control-CA), (b) choline deficient diet (CDD), (c) standard diet and carnitine in drinking water 0.15% w/v (CARN) and (d) choline deficient diet and carnitine (CDD+CARN). After four weeks of treatment, we assessed cardiac function under isometric conditions using the Langendorff preparations [Left Ventricular Developed Pressure (LVDP-mmHg), positive and negative first derivative of LVDP were evaluated], measured serum homocysteine and brain natriuretic peptide (BNP) levels and performed histopathology analyses. In the CDD group a compromised myocardium contractility compared to control (P=0.01), as assessed by LVDP, was noted along with a significantly impaired diastolic left ventricular function, as assessed by (-) dp/dt (P=0.02) that were prevented by carnitine. Systolic force, assessed by (+) dp/dt, showed no statistical difference between groups. A significant increase in serum BNP concentration was found in the CDD group (P<0.004) which was attenuated by carnitine (P<0.05), whereas homocysteine presented contradictory results (higher in the CDD+CARN group). Heart histopathology revealed a lymphocytic infiltration of myocardium and valves in the CDD group that was reduced by carnitine. In conclusion, choline deficiency in adult rats impairs heart performance; carnitine acts against these changes.

Induction of heart valve lesions by small-molecule ALK5 inhibitors.

Aberrant signaling by transforming growth factor-ß (TGF-ß) and its type I (ALK5) receptor has been implicated in a number of human diseases and this pathway is considered a potential target for therapeutic intervention. Transforming growth factor-ß signaling via ALK5 plays a critical role during heart development, but the role of ALK5 in the adult heart is poorly understood. In the current study, the preclinical toxicology of ALK5 inhibitors from two different chemistry scaffolds was explored. Ten-week-old female Han Wistar rats received test compounds by the oral route for three to seven days. Both compounds induced histopathologic heart valve lesions characterized by hemorrhage, inflammation, degeneration, and proliferation of valvular interstitial cells. The pathology was observed in all animals, at all doses tested, and occurred in all four heart valves. Immunohistochemical analysis of ALK5 in rat hearts revealed expression in the valves, but not in the myocardium. Compared to control animals, protein levels of ALK5 were unchanged in the heart valves of treated animals. We also observed a physeal dysplasia in the femoro-tibial joint of rats treated with ALK5 inhibitors, a finding consistent with a pharmacological effect described previously with ALK5 inhibitors. Overall, these findings suggest that TGF-ß signaling via ALK5 plays a critical role in maintaining heart valve integrity.

Drug-induced valvulopathy: an update.

Drug-induced valvulopathy is a serious liability for certain compound classes in development and for some marketed drugs intended for human use. Reports of valvulopathy led to the withdrawal of fenfluramines (anorexigens) and pergolide (antiparkinson drug) from the United States market in 1997 and 2007, respectively. The mechanism responsible for the pathogenesis of valvulopathy by these drugs is likely a result of an "off-target" effect via activation of 5-hydroxytryptamine (5-HT) 2B receptor (5-HT2BR) expressed on heart valve leaflets. Microscopically, the affected valve leaflets showed plaques of proliferative myofibroblasts in an abundant extracellular matrix, composed primarily of glycosaminoglycans. However, the valvular effects caused by fenfluramines and pergolide were not initially predicted from routine preclinical toxicity studies, and to date there are no specific validated animal models or preclinical/toxicologic screens to accurately predict drug-induced valvulopathy. This review covers the structure and function of heart valves and highlights major advances toward understanding the 5-HT2BR-mediated pathogenesis of the lesion and subsequently, development of appropriate animal models using novel techniques/experiments, use of functional screens against 5-HT2BR, and more consistent sampling and pathologic evaluation of valves in preclinical studies that will aid in avoidance of future drug-induced valvulopathy in humans.

Reduction of arteriosclerotic nanoplaque formation and size by n-3 fatty acids in patients after valvular defect operation.

BACKGROUND/METHODS: Coating a silica surface with the isolated lipoprotein receptor heparan sulfate proteoglycan (HS-PG) from arterial endothelium and vascular matrices, we could observe the very earliest stages of arteriosclerotic plaque development by ellipsometric techniques in vitro (patent EP 0 946 876). This so-called nanoplaque formation is represented by the ternary aggregational complex of the HS-PG receptor, lipoprotein particles and calcium ions. The model was validated in several clinical studies on statins in cardiovascular high-risk patients applying their native blood lipoprotein fractions. RESULTS: In 7 patients who had undergone a valvular defect operation, the reduction of arteriosclerotic nanoplaque formation in normal Krebs solution amounted to 6.1 +/- 2.3% (p < 0.0156) and of nanoplaque size to 37.5 +/- 13.2% (p < 0.0312), respectively, after a 3-month therapy with n-3 fatty acids (3 ..3 g daily, Ameu 500 mg). Additionally, the quotient oxLDL/LDL was lowered by 6.8 +/- 2.1% (p < 0.0166), the MDA concentration remained unchanged and the lipoprotein(a) concentration decreased by 15.8 +/- 5.6% (p < 0.0469) in the patients' blood. The concentration of the nanoplaque promoting particles VLDL and total triglycerides was diminished by 34.1 +/- 11.6% (p < 0.0469) and 26.7 +/- 10.8% (p < 0.0156), respectively. Furthermore, the ratio of the strongly atherogenic small dense to the total LDL cholesterol (LDL5+LDL6)/LDLtot decreased by 9.9 +/- 3.0% (p < 0.0174). CONCLUSIONS: A combinatorial regression analysis revealed a basis for a mechanistic explanation of nanoplaque reduction under n-3 fatty acid treatment. This effect was possibly due to the beneficial changes in lipid concentrations and an attenuation of the risk factors oxLDL/LDL and (LDL5+LDL6)/LDLtot.

[Calcification of heart valves in hemodialized patients and their cardiosurgical correction]. / Kalcyfikacja zastawek serca u chorych hemodializowanych i ich kardiochirurgiczna korekta.

Development of vascular and systemic calcification is one of the more serious and often occurring complications in hemodialyzed patients. The cardiac valves calcifications are of the essential importance. They are result of the very complicated calcification process connected with hyperphosphataemia, hyperparathyroidism, calcium carbonate administering and active vitamin D3 metabolites as well as using dialysis fluids with high concentration of calcium. Elevated P and Ca x P product are both significant predictors of cardiovascular mortality in hemodialized patients. We describe two patients with cardiac failure because of cardiac valves calcification. Both patients underwent artificial valves implantation. The patients showed a marked improvement of the quality of life and haemodynamic status.

Effects of warm ischemia following harvesting of allograft cardiac valves.

The clinical use of cryopreserved allograft valves is rapidly increasing. Viability of valve leaflet fibroblasts has been proposed to be critical to durability. Harvesting of allograft valves involves variable warm ischemia times, defined as the time from cessation of donor heart beat to initial cooling for transport. This ischemic period has been implicated as one of the more critical periods of injury to leaflet cell, even though adequate characterization of this potentially injurious phase has never been accomplished. The present study was undertaken to characterize the metabolic response to warm ischemia in a porcine valve leaflet model. Valve handling was similar to clinical valve harvest and transport protocols. Injury was assessed by protein (1H) and phosphorus (31P) magnetic resonance spectroscopy of 224 porcine semilunar valves. Leaflets were analyzed over time for lactate accumulation and ATP degradation. A radiolabelled incubation assay (48 valves) was used to measure proline accumulation by fibroblasts. Electron microscopy was performed on 36 valves with varying warm ischemia times. ATP stores were entirely depleted after 2 h hypoxia (p less than 0.05). However, lactate continued to accumulate over 24 h. Although aerobic metabolism ceased after 2 h warm ischemia, anaerobic metabolism continued for up to 24 h, which may represent an extended window for harvesting fresh tissue for allograft valve implantation.